Ambiguity in bone tissue characteristics
as presented in studies on dental implant
planning and placement: a systematic
review
Rejane Faria Ribeiro-Rotta
Christina Lindh
Andrea Castro Pereira
Madeleine Rohlin
Authors’ affiliations:
Rejane Faria Ribeiro-Rotta, Department of Oral Medicine, School of Dentistry, Federal University of Goia´s, Goia´s, Brazil
Rejane Faria Ribeiro-Rotta, Department of Oral and Maxillofacial Radiology, Faculty of Odontology, Malmo¨ University, Malmo¨, Sweden
Christina Lindh, Department of Oral and Maxillofacial Radiology, Faculty of Odontology, Malmo¨ University, Malmo¨, Sweden
Andrea Castro Pereira, School of Dentistry, Federal University of Goia´s, Goia´s, Brazil
Madeleine Rohlin, Department of Oral and
Maxillofacial Radiology, Faculty of Odontology, Malmo¨ University, Malmo¨, Sweden
Corresponding author: Rejane Faria Ribeiro-Rotta Rua C-235 n. 1323/1501 Nova Suı´c¸a Goiaˆnia-GO 74280-130
Brazil
Tel.:/Fax: þ 55 62 3209 6067 e-mail: rejanefrr@gmail.com
Key words:bone density, dental implant, systematic literature review Abstract
Objectives: To survey definitions of bone tissue characteristics and methods of assessing them in studies of dental implant planning and placement.
Material and methodology: Three databases were searched using specified indexing terms. Three reviewers selected from the titles and retrieved abstracts in accordance with inclusion and exclusion criteria. Descriptions of bone tissue characteristics (bone quality, density and quantity) used before or during dental implant placement were searched for and categorized.
Results: The search yielded 488 titles. One hundred and fort-nine publications were selected and read in full text. One hundred and eight were considered relevant. There were many different definitions and classification systems for bone tissue characteristics and examination protocols. Approximately two-third of the included publications reported the Lekholm & Zarb classification system for bone quality and quantity. However, only four studies implemented the Lekholm & Zarb system as originally proposed. A few publications described bone quality in accordance with the Misch or Trisi and Rao classifications systems. Assessment methods were often described only briefly (or not at all in one-fifth of the publications). Only one study presented the diagnostic accuracy of the assessment method, while only two presented observer performance.
Conclusion: The differing definitions and classification systems applied to dental implant planning and placement make it impossible to compare the results of various studies, particularly with respect to whether bone quality or quantity affect treatment outcomes. A consistent classification system for bone tissue characteristics is needed, as well as an appropriate description of bone tissue assessment methods, their diagnostic accuracy and observer performance.
The justification for assessing jawbone tissue in endosseous dental implant treatment is twofold: (1) as a diagnostic tool to assess whether the jawbone tissue is sufficient for implant treat-ment; (2) as a prognostic tool to predict the probability of success or failure, as the bone tissue characteristics of quality, quantity and density are considered important with regard to treat-ment outcomes (Friberg et al. 1991). However, it is not evident from the literature what bone quality, bone quantity or bone density represent. It is even difficult to find definitions of these terms in studies whose main objective was to evaluate bone tissue characteristics and treat-ment outcomes (Engquist et al. 1988; Jaffin & Berman 1991; Jemt 1993; Friberg et al. 1995, 1999; Jemt & Lekholm 1995; Razavi et al. 1995; Truhlar et al. 1997a, 1997b; Trisi & Rao 1999; Bahat 2000; O’Sullivan et al. 2000; Choel et al. 2003; Locante 2004; Herrmann et al. 2005).
A classification system for jaw anatomy (jaw shape and quality) frequently referred to in pub-lications on endosseous dental implant treatment was proposed by Lekholm & Zarb (1985). The system is presented as drawings of the jaws accompanied by text, and assessment methods to classify the bone tissue are recommended. Bone quality is broken down into four groups according to the proportion and structure of compact and trabecular bone tissue, and the quantity of jawbone is broken down into five groups, based on residual jaw shape following tooth extraction. Other classifications of bone tissue have also been used in studies of dental implants (Misch 1990b; Trisi & Rao 1999). Differing classification systems for bone tissue characteristics may lead to confusion and inter-fere with attempts to compare the results of various studies. Furthermore, the evidence for the efficacy of clinical methods to assess jawbone Date:
Accepted 7 July 2010
To cite this article:
Ribeiro-Rotta RF, Lindh C, Pereira AC, Rohlin M. Ambiguity in bone tissue characteristics as presented in studies on dental implant planning and placement: a systematic review.
Clin. Oral Impl. Res. xx, 2010; 000–000. doi: 10.1111/j.1600-0501.2010.02041.x
tissue before endosseous dental implant treat-ment is sparse (Ribeiro-Rotta et al. 2007).
The aim of this review was to survey definitions used for bone tissue characteristics (bone quality, bone quantity and bone density) and the assess-ment methods utilized to characterize bone tissue in studies on endosseous dental implant planning and placement. The target audience consists of clinicians who treat patients with dental implants, as well as related field professionals.
Methodology for the review of the
literature
To ensure a systematic approach, review of the literature was conducted and adapted to Good-man’s model (1996), consisting of the following steps: (1) problem specification, (2) formulation of a plan for the literature search, (3) literature search and retrieval of publications and (4) data extraction and interpretation.
Problem specification
For the assessment of jawbone tissue before or during endosseous dental implant placement: What definitions of bone tissue
characteris-tics (bone quality, bone quantity and bone density) can be found in original studies? What methods were used to assess bone
tissue characteristics and how were the meth-ods described?
Formal definitions for the following elements were sought before the literature search: Definition ¼ the act or process of stating a
precise meaning or significance; formulation of a meaning (The American Heritage Dic-tionary).
Quality ¼ degree or grade of excellence (The American Heritage Dictionary).
Quantity ¼ a specified or indefinite number or amount; the measurable, countable or compar-able property or aspect of a thing (The Amer-ican Heritage dictionary); the aspect in which a thing is measurable in terms of greater, less or equal or of increasing or decreasing magnitude (Merriam-Webster Online Dictionary). Bone density ¼ the amount of mineral per
square centimeter of BONE. This is the defini-tion used in clinical practice. Actual bone density would be expressed in grams per milli-liter. It is most frequently measured by photon absorptiometry or X-ray computed tomography (National Library of Medicine, MeSH browser).
Formulation of a plan for the literature search Searches were limited to publications with abstracts, published in English, conducted on
human tissues and on individuals older than 19. Specific limits were used to search three data-bases as follows:
PubMed: Entrez date 01/01/1966/ to 9/2/ 2005 (first strategy) and 1/1/1966 to 6/7/ 2009 (second strategy), all adults 19 or older, and publications indexed as ‘‘item with ab-stracts,’’ ‘‘English,’’ and ‘‘Human.’’ The Cochrane Library (including Cochrane
Database of Systematic Reviews [Cochrane Reviews], Database of Abstracts of Reviews of Effects [Other Reviews] and Cochrane Central Register of Controlled Trials [Clin-ical Trials]): Date range 1800 to 2009, all records status.
Web of Science electronic databases: Time span from 1986 to 2009, all citation data-bases.
To ensure the widest possible search, the indexing terms were used as MeSH terms and free text in the PubMed search, and the trunca-tion symbol (n
) was used in the Cochrane Library and Web of Science searches. Publications on primary material and systematic reviews that shed light on problem specifications were in-cluded. Case reports, book chapters and narrative reviews were excluded, as well as publications on local bone reaction (healing), the temporoman-dibular joint, bone grafts and dental implants for orthodontic treatment.
Literature search and retrieval of publications Three of the authors independently read all re-trieved titles and abstracts. When at least one author regarded a publication as having met the inclusion criteria, it was ordered and read in full text. A publication was considered relevant when one or more of the terms of bone quality, bone quantity or bone density was found in the ab-stract. When no explicit definition of bone tissue or examination protocol was found but was nevertheless referred to, the study in which the reference appeared was retrieved. Relevant pub-lications in the reference lists of the systematic reviews were retrieved. No systematic hand search of the reference lists of other included publications was performed.
Data extraction and interpretation
With a focus on definitions of bone tissue char-acteristics – bone quality, bone quantity and bone density – material and methods, results and tables of the included publications were read and analyzed using a protocol. The text on assessment methods underpinning the definition of bone tissue was also analyzed. The most commonly used abbreviations, definitions and measurement units for the assessment of bone
quality, bone quantity and bone density were listed to enable a better overview (Table 1). The data from the included publications were then listed in tables, along with the main topics related to the problem specifications (assessment methods, classification of jawbone tissue and measurement units) in order to standardize the interpretation of data.
Results
Literature search
The PubMed search yielded 250 titles and ab-stracts, the Cochrane Library search yielded an additional 148 titles and abstracts, and the Web of Science yielded an additional 90 titles and ab-stracts. From these titles and abstracts, 149 pub-lications were deemed to meet the inclusion criteria and read in full text. Of these publica-tions, 108 were considered relevant after data extraction and interpretation.
Interpretation of data on bone tissue charac-teristics presented in the included publications Overall results
There was a diversity of definitions/classifica-tions of bone tissue characteristics and examina-tion protocols. It was difficult, sometimes impossible, to understand how the bone tissue had been assessed. The diagnostic accuracy of the method used to assess bone tissue was presented in terms of correct diagnoses in only one study (Lindh et al. 1996a), and observer performance of the method was presented in only two studies (Lindh et al. 1996a; Shapurian et al. 2006).
The classification of jawbone tissue proposed by Lekholm & Zarb (1985) was referred to in about two-thirds of the included publications (Tables 2–5). A few publications described bone quality according to Misch (1990b) (Tables 7 and 8) or Trisi & Rao (1999) (Tables 7 and 8). Bone quality was described alone or together with bone density or bone quantity in 22 publications, without referring to Lekholm & Zarb (Tables 6 and 7). Bone density alone was addressed in 18 publications (Table 8). Assessment methods var-ied and the description of the methods was often brief. About one-fifth of the publications (n ¼ 19) contained no account of the assessment methods used (Tables 3–5 and 7).
Publications that referred to Lekholm & Zarb (1985) Table 2 presents four publications (Johns et al. 1992; Fartash et al. 1996; Bergendal & Engquist 1998; van Steenberghe et al. 2002), that described the classification of jawbone tissue and the as-sessment methods (radiography and explorative drilling at implant placement) in accordance with the original description by Lekholm &
Zarb (Fig. 1). Bone quality was categorized into four groups: groups 1–4 in two publications (Johns et al. 1992; Fartash et al. 1996), groups A–D in one (Bergendal & Engquist 1998) and scores I–IV in another (van Steenberghe et al. 2002). No publication described bone tissue as
residual jaw shape or contour A–E in accordance with Lekholm & Zarb (Fig. 1). Instead, bone quantity was mentioned and sometimes consid-ered synonymous with the anatomy of bone or degree of resorption (Fartash et al. 1996). One publication (Bergendal & Engquist 1998)
pre-sented bone quality and bone quantity as a morphological characterization of jawbone. The description of examination methods was explicit, but the methods varied among the four studies.
Table 3 shows 31 publications that presented jawbone tissue in line with the original classifi-Table 1. List of abbreviations and definitions of the clinical methods and measurement units to assess bone quality, bone quantity and bone density related to endosseous dental implant planning and placement
Abbreviation Meaning Definition
BMC Bone mineral content The degree of bone mineralization
BMD Bone mineral density
Bone mass density
Bone density – the amount of mineral per square centimeter of bone, expressed in grams per milliliter (National Library of Medicine, MeSH browser)
CT Computed tomography Tomography, X-ray CT using X-ray transmission and a computer algorithm to reconstruct the image (National Library of Medicine, MeSH browser)
DXA or DEXA
Dual energy X-ray absorptiometry
An imaging technique that uses two low-dose X-ray beams with different levels of energy to produce a detailed image of body components; used primarily to measure bone mineral density (Dorland’s Illustrated Medical Dictionary).
Absorptiometry, photon – a non-invasive method for assessing body composition. It is based on the differential absorption of X-rays (or g rays) by different tissues such as bone, fat and other soft tissues. The source of (X-ray or g-ray) photon beam is generated either from radioisotopes such as Gadolinium 153, Iodine 125 or Americum 241 which emit g rays in the appropriate range; or from an X-ray tube, which produces X-rays in the desired range. It is primarily used for quantitating bone mineral content, especially for the diagnosis of osteoporosis, and also in measuring bone mineralization (National Library of Medicine, MeSH browser)
————— Implant stability Resistance to unscrewing (Friberg 1994) ISQi Implant stability quotient
at implant placement
The ISQ measured at implant placement (Bischof et al. 2004) L&Z Lekholm & Zarb
classification
Classification of bone quantity and bone quality in dental implant field established by Lekholm & Zarb and based on preoperative radiographs and explorative drilling at implant site preparation. The residual jaw shape and different rates of bone resorption following tooth extraction are rated in 5 general groups from A to E. Bone quality comprises four groups from 1 to 4, depending on the amount of compact and cancellous bone present (Lekholm & Zarb 1985)
Micro-MRI Micro or high-resolution magnetic resonance imaging
Non-invasive and radiation-free method considered as a potential imaging tool that could provide clinical evaluation of trabecular bone architecture and quality (Choel et al. 2004)
MRI Magnetic resonance
imaging
Non-invasive method of demonstrating internal anatomy based on the principle that atomic nuclei in a strong magnetic field absorb pulses of radiofrequency energy and emit them as radio waves that can be reconstructed into computerized images. The concept includes proton spin tomographic techniques (National Library of Medicine, MeSH browser)
PTV Periotest values Numerical value computed converted from contact time value. Periotest is an electronic device for measuring the damping characteristics of the periodontium and stability of oral implants. It measures the contact time between the rod and the tapped object and the shorter contact time (milliseconds), the more stable periodontium or implant/ bone contact (Schulte & Lukas 1993)
QCT Quantitative computed
tomography
Accurate and reproducible CT for quantitative analyses of the bone mineral density, by using a reference phantom (Taguchi et al. 1991)
RFA Resonance frequency
analyses
Method to evaluate implant stability, by using a small beam-like piezo-ceramic transducer. Vibration and response are registered (Hz) (Meredith et al. 1996)
SXA Single-energy X-ray
absorptiometry
A method of assessing bone mineral density using a single energy X-ray beam (Dorland’s Illustrated Medical Dictionary)
TBPf Trabecular bone pattern factor
This factor is based on the idea that the connectedness of cancellous bone structures in a two-dimensional section can be described by the relation of convex to concave structures. Owing to the calculation formula, the trabecular interconnection is higher, the more negative the value (Ulm et al. 1997)
TBV Trabecular bone volume Fractional area of the trabeculae expressed as the percentage of mineralized bone tissue within a region of interest (Lindh et al. 1996b, 1997)
TTBV Total trabecular bone volume
Fractional area of the trabeculae, including the transitional area to cortical bone, expressed as the percentage of mineralized bone tissue within a region of interest (Lindh et al. 1996b, 1997)
————— Cutting torque A rotatory force applied during low-speed tapping, and according to Johansson & Strid 1994, this technique measures the electric current used during threading. It consists of two parts: true cutting resistance and the friction (surface resistance)
————— Cutting resistance or true cutting resistance
The determination of the torque exerted by the low-speed motor while tapping a drilled hole with a crew tap or a self-tapping implant being forces like friction subtracted. OR Energy needed for cutting out a specific amount of bone material with the screw tap. It is conveniently presented in J/mm3(Johansson & Strid 1994)
————— Histomorphometry The quantitative measurement and characterization of microscopical images using a computer; manual or automated digital image analysis typically involves measurements and comparisons of selected geometric areas, perimeters, length angle of orientation, form factors, center of gravity coordinates, and image enhancement (Stedman’s Online Medical Dictionary)
————— Microradiography Production of a radiographic image of a small or very thin object on fine-grained photographic film under conditions that permit subsequent microscopic examination or enlargement of the radiograph at linear magnifications of up to several hundreds and with a resolution approaching the resolving power of the photographic emulsion (about 1000 lines per millimeter) (National Library of Medicine, MeSH browser) ————— Peak insertion torque The top or upper limit (positive or negative, maximum or minimum) of the insertion torque (Friberg 1994) ————— Pull-out resistance The pull-out force required to remove the implant from the jaws (Kido et al. 1997)
cation by Lekholm & Zarb, but the description of assessment methods was incomplete. Most pub-lications grouped bone quality in grades or scores of 1–4 and bone quantity in grades (scores) of A–E or A–D. Four publications (Becker et al. 1997, 1998, 1999; Herrmann et al. 2007) regarded jaw shape as equivalent to quantity. Radiography and assessment at implant placement were men-tioned in five publications (Bass & Triplett 1991; Hutton et al. 1995; Becker et al. 1999; Friberg et al. 2003; Alsaadi et al. 2008), while there was a description of only one assessment method in 19 other publication (Friberg et al. 1992; Jemt 1994; Becker & Becker 1995; Becker et al. 1997, 1998, 2000a, 2000b, 2005; Jagger et al. 2001; Attard & Zarb 2002; Friberg et al. 2002; Calandriello et al. 2003; Rocci et al. 2003; Bergkvist et al. 2004; Ostman et al. 2005, 2006; Ottoni et al. 2005; Montes et al. 2007; Collaert & De Bruyn 2008).
Table 4 presents 26 publications (Truhlar et al. 1994a, 1994b, 1997a, 1997b, 1997c, 2000a, 2000b; Oikarinen et al. 1995; Lindh et al. 1996b; Orenstein et al. 1998; Friberg et al. 1999; Orenstein et al. 2000; O’Sullivan et al. 2000; Spray et al. 2000; Shimpuku et al. 2003; Tawil & Younan 2003; Attard & Zarb 2004; Shin et al. 2004; Zix et al. 2005; Romeo et al. 2006; Shapurian et al. 2006; Achilli et al. 2007; Alsaadi et al. 2007; Huwiler et al. 2007; Siepenkothen 2007; Ganeles et al. 2008) that referred to the classification by Lekholm & Zarb but described bone quality only. Bone quality was classified as quality 1–4 or type I–IV in most publications. In some publications (Spray et al. 2000; Truhlar et al. 2000a, 2000b; Achilli et al. 2007; Alsaadi et al. 2007), bone quality was regarded as synon-ymous with bone density. Bone quality was related to trabecular bone pattern as assessed by periapical radiography (Lindh et al. 1996b), re-lated to bone density as assessed in Hounsfiled
Units (HU) by computed tomography (CT) (Sha-purian et al. 2006), related to implant stability as assessed by insertion torque (O’Sullivan et al. 2000) and by RFA values (Huwiler et al. 2007). The description of assessment methods varied.
Seven publications (Friberg et al. 1999; Shahlaie et al. 2003; Aalam & Nowzari 2005; Aalam et al. 2005; Aranyarachkul et al. 2005; Blanes et al. 2007; Lee et al. 2007) that referred to Lekholm & Zarb (Table 5) described jawbone tissue only in terms of bone density, an expression not used by Lekholm & Zarb. Two publications by the same authors (Aalam & Nowzari 2005; Aalam et al. 2005) classified bone tissue into two categories, two publications (Friberg et al. 1999; Blanes et al. 2007) used three categories and the other three publications (Shahlaie et al. 2003; Aranyarachkul et al. 2005; Lee et al. 2007) used four categories. Publications with other descriptions of jawbone tissue As shown in Table 6, bone quality was combined with either bone density (Friberg et al. 1995; Choel et al. 2003, 2004) or bone quantity (Saa-doun & LeGall 1992; Razavi et al. 1995; Jemt & Hager 2006). Four studies of human cadavers analyzed jawbone tissue in detail. Bone architec-ture was described by Choel et al. (2004) and Razavi et al. (1995) and the amount of mineral by Friberg et al. (1995) and Choel et al. (2003, 2004). Bone quantity was presented as (1) depth of bone (Saadoun & LeGall 1992), (2) mean bone height (Razavi et al. 1995) and (3) bone resorption index (Jemt & Hager 2006).
Sixteen publications (Manz 1997, 2000; Walker et al. 1997; Gaucher et al. 2001; Khang et al. 2001; Ibanez & Jalbout 2002; Testori et al. 2002; Lettry et al. 2003; Weng et al. 2003; Chou et al. 2004; Kourtis et al. 2004; Morris et al. 2004; Elkhoury et al. 2005; Sullivan et al. 2005; Degidi et al. 2007; Orsini et al. 2007) described jawbone tissue in terms of bone quality only (Table 7).
The system proposed by Trisi & Rao (1999) with three classes (dense, normal and soft bone) was used in five publications (Gaucher et al. 2001; Khang et al. 2001; Testori et al. 2002; Weng et al. 2003; Sullivan et al. 2005), and the system by Misch (1990b) with four groups (D1–D4) was used in two other publications (Degidi et al. 2007; Orsini et al. 2007). One publication did not refer to any classification system, but bone quality was classified according to a scale of D1–D4 (Kourtis et al. 2004). The assessment methods varied.
Bone density was presented as the sole jawbone tissue characteristic in 18 publications (Lindh et al. 1996a, 1997; Kido et al. 1997; Taguchi et al. 1997; Misch et al. 1999a, 1999b; Homolka et al. 2001, 2002; Beer et al. 2003; Nkenke et al. 2003; Moheng & Feryn 2005; Turkyilmaz et al. 2006, 2007a, 2007b, 2008a, 2008b; Gulsahi et al. 2007; Yang et al. 2008) (Table 8), of which eight were performed on human cadaver jaws. Different classification systems and measure-ment units were used, such as as the amount of calcium hydroxyapatite expressed in mg/cm3 (Lindh et al. 1996a, 1997; Kido et al. 1997; Homolka et al. 2001, 2002; Beer et al. 2003; Nkenke et al. 2003), in g/cm2(Gulsahi et al.
2007), in percentage of mineralized bone tissue (Lindh et al. 1997), in buccal and oral cortical bone volume trabecular bone volume (Nkenke et al. 2003), in intertrabecular connectivity (Nkenke et al. 2003) or in HU (Taguchi et al. 1997; Moheng & Feryn 2005; Turkyilmaz et al. 2006, 2007a, 2007b, 2008a, 2008b). Most of these publications performed CT (Taguchi et al. 1997; Moheng & Feryn 2005; Turkyilmaz et al. 2006, 2007a, 2007b, 2008a, 2008b), quantitative computed tomography (Lindh et al. 1996a, 1997; Kido et al. 1997; Homolka et al. 2001, 2002; Beer et al. 2003; Nkenke et al. 2003), DEXA (Gulsahi et al. 2007) or weight and volume measurements (Misch et al. 1999b) to assess bone tissue. Table 2. Publications on planning and placement of dental implants where the description of assessment methods and classification of jawbone tissue proposed by Lekholm and Zarb (1985) (Fig. 1) was described in accordance with the original description
References Assessment methods Classification of jawbone tissue
measurement unit
Comments
Johns et al. (1992) Radiography Bone quality (bone types 1–4) John et al.: Panoramic radiography, lateral cephalography At implant placement Bone quantity (bone resorption)
bone types A–E
Evaluation at implant placement made independently of radiography. Correlation presented in the table Fartash et al. (1996) Radiography Bone quality 1–4 Fartash et al.: Panoramic survey, lateral cephalogram,
axial view and intra-oral films At implant placement Anatomy of jawbone and
degree of resorption A–E (bone quantity)
Tactile evaluation during surgery
Bergendal & Engquist (1998) Radiography Bone quality A–D Bergendal & Engquist: Panoramic and lateral cephalography, tomographic examinations in some regions
At implant placement Bone quantity 1–5 Visual inspection and tactile perception
van Steenberghe et al. (2002) Clinical assessment Bone quality: scores I–IV van Steenberghe et al.: Panoramic radiography, computed tomography of some regions
Radiography Bone quantity
(bone resorption): scores A–E
Tactile assessment, eye inspection at implant placement At implant placement
Discussion
Methodology for the literature search and data interpretation
Only the first step of the search strategy was systematic. The second step of searching the reference lists of included studies, a common approach in systematic reviews of intervention methods, was not performed. We felt that the aim of the study had been achieved with the data-base searches. However, to ensure the retrieval
of many publications, the search strategies com-prised three databases – PubMed, Cochrane Li-brary and Web of Science. The search of at least two electronic sources is regarded as improving the methodological quality of a systematic re-view (Shea et al. 2007). The use of the truncation symbol permits the identification of alternative spellings after the root word, which may vary according to the database used. Studies of human cadavers were included, as data from these studies could be used to validate the assessment
methods used for clinical examination of jaw-bone tissue.
Medical Subject Headings (MeSH) is a con-trolled vocabulary designed by the National Li-brary of Medicine to search PubMed and other health science databases. This review used it primarily to establish the formal definition of the element problems. Bone density is a MeSH term, but bone quantity and bone quality are not. Four well-known English dictionaries (American Heritage Dictionary; Merriam-Webster Online Table 3. Publications on planning and placement of dental implants where the description of assessment methods and classification of jawbone tissue proposed by Lekholm and Zarb (1985) (Fig. 1) was referred to
References Classification measurement unit Comments
Assessment methods: Radiography and evaluation at implant placement
Bass & Triplett (1991) Jawbone anatomy: scores 1–4 Bass & Triplett: Panoramic and periapical radiography, lateral cephalography, tomography of some regions. No description of method at implant placement Resorption anatomy: scores 1–5
Hutton et al. (1995) Bone quality/morphology: quality 1–4 Hutton et al.: Lateral cephalography, panoramic radiography. No description of method at implant placement
Friberg et al. (2003) Bone quantity/bone resorption: A–E Friberg et al.: No description of methods
Becker et al. (1999) Bone quality 1–4 Becker et al.: Periapical radiographs and linear tomograms. No description of method at implant placement
Alsaadi et al. (2008) Bone quantity (jaw shape) A–E Alsaadi et al.: No description of radiographic method.
Tactile evaluation during drilling. Bone resorption ¼ bone volume Assessment method: Only radiography mentioned
Becker & Becker (1995) Bone quality: scores 1–4 Becker & Becker: Panoramic and periapical radiography Friberg et al. (2002) Bone quantity: scores A–E Friberg et al.: No description of radiographic method
Becker et al. (1997) Bone quality type 1–4 Becker et al. (1997): Panoramic radiography supplemented with periapical radiography and linear and computerized tomography Becker et al. (1998) Bone quantity (shape) A–D Becker et al. (1998): Linear tomography
Becker et al. (2005) Becker et al. (2005): Panoramic and periapical radiography. Linear tomography
Calandriello et al. (2003) Bone quality: 1–4 Calandriello et al.: No description of radiographic method. Mention low and high bone density
Bone quantity: A–C
Ottoni et al. (2005) Bone quality: types 1–3 Ottoni et al.: Panoramic radiography and tomography Bone quantity: A–B
Jagger et al. (2001) Bone quality: modified from Lekholm & Zarb classification – 1–3
Jagger et al.: Dental panoramic tomography Bone quantity: modified from
Lekholm
& Zarb classification – 1–3
Montes et al. (2007) Bone types II/III and B/C Montes et al.: Panoramic radiography and periapical radiography Assessment method: Only examination during drilling/at the time of surgery or fixture insertion mentioned Friberg et al. (1992) Bone quality: types 1–4 Friberg et al.: Bone quality type 1 ¼ hard bone; type 4 ¼ soft bone
Jemt (1994) Jemt: Bone quality: 1 (hardest) – 4 (softest), Jawbone anatomy: – E
(most severely resorbed). No description of method
Becker et al. (2000b) Becker et al.: Subjectively scored, no description of method
Attard & Zarb (2002) Bone quantity/jawbone shapes: A–E Attard & Zarb: No description of method
Rocci et al. (2003) Rocci et al.: Bone quantity said to be determined but not presented
Bergkvist et al. (2004) Bergkvist et al.: No description of method
O¨ stman et al. (2006) O¨ stman et al.: Bone quality assessed on resistance of bone during drilling at implant placement
O¨ stman et al. (2005) Bone quality: type 1–4 O¨ stman et al.: No description of method Becker et al. (2000a) Bone quantity: A–D Becker et al.: No description of method Collaert & De Bruyn (2008) Collaert & De Bruyn: No description of method
Assessment method: Not mentioned
Grunder et al. (1999) Bone quality: 1–4 and unknown Grunder et al.: Classification of bone quality and bone quantity stated in Tables Bone quantity: A–E and unknown
Ivanoff et al. (1999) Bone quality: 1–4 Ivanoff et al.: Classification of bone quality and bone quantity stated in Tables Malo´ et al. (2006) Bone quantity: A–E Malo´ et al.: Bone quality considered synonymous with bone density (p 225) Friberg et al. (2005) Friberg et al.: Refer to Friberg & Billstro¨m (2002)
Herrmann et al. (2005) Jawbone quality 1–4 Hermann et al. (2005, 2007): Jawbone quality (density) and jaw shape (quantity). Different jaw shape/bone quality combinations were evaluated
Herrmann et al. (2007) Jaw shape A–E
Becker et al. (1998) Bone quality: type 1–4 Becker et al.: Bone quality type 4 considered low bone density Bone quantity (jaw/bone shape): A–D
Dictionary; Dorland’s Illustrated Medical Dic-tionary and Stedman’s Online Medical Diction-ary) were consulted for the definition of element problems not included in the MeSH.
An a priori protocol and tables with main topics related to the problem specifications were used to standardize data extraction and interpre-tation. The tables facilitated the structuring of the publications into groups according to simila-rities and dissimilasimila-rities among the bone tissue classification systems and assessment methods utilized.
Results
Classification systems are needed in order to provide a framework for the orderly, scientific study of treatment and treatment outcomes. Our review documents deficiencies in the use of
classification systems for dental implant plan-ning and placement. The included studies pre-sented a diversity of classification systems and measurement units. Description of bone quantity and quality even varied from one publication to another by the same authors. Furthermore, many studies made it impossible to interpret not only how the bone tissue had been classified but also how the bone tissue had been examined and the results of the examination assessed. Authors should not only provide clear details of the primary and secondary outcomes of the interven-tion under study, but describe how these out-comes have been measured and whether any particular steps have been taken to increase the reliability of the measurements (Altman et al. 2001; Moher et al. 2001). The reliability of the methods used and the assessment of jawbone tissue were reported in only two publications.
This is an inadequate approach to research as inaccuracy of measurements can affect the re-ported results of any intervention.
The classification system proposed by Le-kholm & Zarb (1985) was referred to in most studies. However, only four of 80 retrieved stu-dies that referred to Lekholm & Zarb (1985) actually followed the original description of the classification system and the recommended methods. It seemed as though it had become routine to include the reference by Lekholm & Zarb (1985), apparently without knowledge of the original description of either bone character-istics or the recommended assessment methods. The original publication by Lekholm & Zarb (1985) contains no definitions of bone character-istics. The suggestion that anatomical features of bone tissue be considered before the preparation of implant sites was based on experience. The Table 4. Publications on planning and placement of dental implants where the description of assessment methods and classification of jawbone tissue proposed by Lekholm and Zarb (1985) was referred to
References Classification measurement unit Comments
Assessment methods: Radiography and evaluation during drilling/at implant placement Truhlar et al. (1994a)
Truhlar et al. (1994b)
Bone quality (BQ): Quality 1–4 Truhlar et al. (1994a, 1994b): Tactile sensation during implant site preparation; no description of radiographic method
Truhlar et al. (1997a) Truhlar et al. (1997a): Clinical evaluation during site preparation: No description of radiographic method
Truhlar et al. (1997c) Truhlar et al. (1997c): Tactile sensation of cutting resistance and force required during surgery, panoramic, radiography and reformatted CT Truhlar et al. (2000b) Truhlar et al. (2000b): Subjective clinical evaluation during site preparation:
No description of radiographic method. BQ ¼ bone density
Orenstein et al. (2000) Orenstein et al. (2000): Tactile sensation during preparation of implant site; no description of radiographic method
Spray et al. (2000) Spray et al.: Tactile sensations during implant preparation;
no description of radiographic method. In fig. 8 BQ ¼ bone density Orenstein et al. (1998) Bone density: Q-1, Q-2, Q-3, Q-4
and unknown
Orenstein et al. (1998): Tactile sensations during the preparation of the implant site; no description of radiographic method
Attard & Zarb (2004) BQ (types I–IV) Attard & Zarb: No description of methods Assessment method: Only radiography mentioned
Lindh et al. (1996b) BQ: Classes 1–4 Lindh et al. (1996b): Lindh: Human cadaver jaws Periapical radiography. Trabecular bone pattern assessed by radiography and related to BQ
Friberg et al. (1999) Friberg et al.: Tomography and lateral cephalography
Shin et al. (2004) Shin et al.: Tomography; no explicit measurement unit for BQ
Tawil & Younan (2003) BQ: types 1–4 Tawil & Younan: Periapical and panoramic radiography, CT of some regions
Zix et al. (2005) Zix et al.: Panoramic radiography
Shapurian et al. (2006) Bone type: 1–4, no bone Shapurian et al.: CT. Bone density assessed in HU and related to BQ Oikarinen et al. (1995) Type I–IV bone Oikarinen et al.: No description of radiographic method
Achilli et al. (2007) BQ: D1–D4 Acilli et al.: Bone quantity according to Howell classes. BQ ¼ bone density Assessment method: Only examination during drilling/at the time of surgery or fixture insertion mentioned Truhlar et al. (1997b) BQ 1–4 Truhlar et al. (1997b): Truhlar: BQ at implant insertion
Romeo et al. (2006) Romeo et al.: Explorative drilling at implant site
Alsaadi et al. (2007) Alsaadi et al.: Tactile sensation during drilling and during implant insertion by torque force measurement device. BQ for cortical bone and trabecular bone classified separately. BQ ¼ trabecular bone density
O’Sullivan et al. (2000) Bone types 2–4 O’Sullivan et al.: Human cadaver jaws. Tactile impression of BQ at placement and appearance of bone at implant site following implant removal. BQ also assessed according to
Johansson & Strid (1994) and classified by insertions torque (N cm)
Huwiler et al. (2007) BQ classification: 1–3 Huwiler et al.: No correlation between BQ and micro CT bone characteristics or RFA values Siepenkothen (2007) BQ types I–IV
Assessment method: Not mentioned Truhlar et al. (2000a) BQ-1, 2, 3 and 4 Truhlar et al. (2000a): BQ ¼ bone density
Shimpuku et al. (2003) BQ type 2/type 3/type 4 Shimpuku et al.:Type 2/3 mentioned in table 4 and type 3/type 4 in table 2 Ganeles et al. (2008) Types I–IV Ganeles et al.: Poor-quality (type IV) bone
Characteristics of jawbone tissue described only as bone quality and the description of assessment methods was incomplete in the publications listed. CT, computed tomography.
foundation for five groups of jaw shapes or four groups of bone quality was not discussed. Other classification systems have been proposed to categorize bone quality into two groups (Aalam & Nowzari 2005; Aalam et al. 2005), three groups (Friberg et al. 1999; Trisi & Rao 1999; Blanes et al. 2007) or four groups of bone density (Misch et al. 1999a). No such categories were discussed in these publications.
Somewhat surprisingly, the frequently used clas-sification system for jawbone tissue described by Lekholm & Zarb (1985) has not been validated. Furthermore, as concluded on the basis of a sys-tematic review, the evidence concerning accuracy and observer performance of clinical methods used to assess bone tissue characteristics before and during dental implant placement is insufficient (Ribeiro-Rotta et al. 2007). When utilizing
systems, such as those proposed by Lekholm & Zarb (1985), Misch (1990b) or Trisi & Rao (1999), knowledge about the efficacy of the assessment method is fundamental. Virtually every visual and tactile piece of information from an examination varies to some degree from patient to patient, while examiners may differ in their ability to detect findings and in their propensity to record them. Even when examiners agree that they are observing Table 5. Publications on planning and placement of dental implants where the description of assessment methods and classification of jawbone tissue proposed by Lekholm and Zarb (1985) (Fig. 1) was referred to
References Classification measurement unit Comments
Assessment methods: Radiography, during drilling and cutting torque measurements Friberg et al. (1999) Bone density: 1(low density, 2
(medium density), 3 (high density) Newton centimeter (N cm)
Friber et al.: No description of radiographic method. Bone density evaluated by torque measurements during implant insertion in
Lee et al. (2007) Subjective radiographic bone density: 1–4 of CT and CBCT scans
Mean HU from CT and CBCT scans Subjective drilling density: D1–D4 Resistance torque in N cm: three scenarios
Lee et al.: Human cadaver jaws. Radiographic rating according to Lekholm & Zarb and rating during drilling according to Misch (1990a) classification
Assessment methods: Only radiography mentioned Shahlaie et al. (2003)
Aranyarachkul et al. (2005)
Subjective bone density class 1–4 Mean HU
Shahlaie et al.: Human cadaver jaws. HU from QCT correlated to subjective assessments of printed images. An overall relationship, but wide ranges of HU within each of four Lekholm & Zarb classes
Aranayarachkul et al.: Human cadaver jaws. HU from QBCT correlated to subjective assessments of printed images. An overall relationship, but wide ranges of HU within each of four Lekholm & Zarb classes
Aalam & Nowzari (2005) Aalam et al. (2005)
Bone types 1 and 2 ¼ high-density bone Bone types 3 and 4 ¼ low-density bone
Aalam & Nowzari; Aalam et al.: Periapical radiography and CT. Bone density classification modified
according to Lekholm & Zarb Assessment method: Not mentioned Blanes et al. (2007) Type I: very dense bone
Type II: cortical and spongy bone Type III: very spongy bone
Blanes et al.: Type I equal to type-I bone according to Lekholm & Zarb, Type II to types II and III and Type III to type IV according to Lekholm & Zarb
Jawbone tissue was described only as bone density or as bone morphology and the description of assessment methods was incomplete in publications listed. CT, computed tomography; CBCT, cone beam computed tomography; HU, Hounsfield units.
Table 6. Bone quality together with either bone density or bone quantity
References Assessment method Classification measurement unit Comments
Bone quality and bone density Friberg et al. (1995) Cutting resistance technique
Morphometry from microradiography
(mJ/mm3)
Total amount of mineralized bone, of trabecular bone and compact bone (% of bone area)
Friberg et al.: Human cadaver jaws. Bone quality assessed by cutting resistance and bone density by morphometry Correlation between bone density and cutting resistance of each implant site was r ¼ 0.9
Choel et al. (2003) DEXA BMC (g)
BMD (quotient of BMC and area) (g/cm2)
Choel et al. (2003, 2004): Slices of human cadaver jaws. BMC and BMD considered as bone quality parameters
Choel et al. (2004) Magnetic resonance imaging
DXA
Trabecular bone architecture: histomorphometric
parameter units, angle between trabeculae/tooth axis
BMD (g/cm2)
Human cadaver jaws. DXA presented as method but results of DXA not reported
Bone quality and bone quantity Saadoun & LeGall
(1992)
At implant placement (clinical examination) Radiography
Bone Quality – spongiosa (type IV); – cortical bone (type I)
Depth of bone (mm)
Saadoun & LeGall: Panoramic and periapical radiography, CT. Own classification of bone quality
Razavi et al. (1995) Microscopy
Caliper measurements
Trabecular distance, cortex thickness, marrow spaces (mm-mm)
Mean height of bone (mm)
Razavi et al.: Maxillae of human cadavers
Jemt & Hager (2006)At surgery Bone quality: fours grades Bone resorption index (minimal, moderate, advanced, extreme)
Jemt & Hager: No description of method and grades of bone quality
Publications on planning and placement of dental implants where jawbone tissue was described as bone quality together with another bone tissue characteristic. BMC, bone mineral content; BMD,bone mineral density; CT, computed tomography; DXA/DEXA, dual energy X-ray absorptiometry.
the same thing, they may apply different percep-tual thresholds. Only two studies of observer performance were used in the index proposed by Lekholm & Zarb (1985), and they were on the radiological part of the index. The reliability of surgeons’ perceptions of bone quality during sur-gery is difficult to investigate. The results of observer performance were contradictory. Shapur-ian et al. (2006) found the observer agreement of two examiners to be low when assessing bone quality as correlated with HU values (r ¼ .65, Po.001), concluding that their finding underscored the subjective nature of the Lekholm & Zarb classification system. On the other hand, Lindh et al. (1996a, 1996b) found the Kappa index for observer agreement to be fair when seven observers assessed the trabecular pattern in intra-oral peria-pical radiographs according to the Lekholm & Zarb classification system. In practice, however, the observers basically used only two of the four classes in their assessment. The applicability of the Le-kholm & Zarb classification of bone quality was also supported by the results of two previous studies. Thus, panoramic radiographic appearances of bone quality assessed according to Lekholm and Zarb was found to be correlated with bone mineral density of the body of the mandible as measured by
dual energy X-ray absorptiometry (Horner & Devlin 1998). Also the results of a more recent study (Bergkvist et al. 2010) presented a high correlation between the classification performed during surgery and measurements of bone mineral density in CT images of correponding implant sites.
Some studies (Truhlar et al. 1994a, 1994b, 1997a, 1997b, 1997c, 2000a, 2000b; Becker et al. 1998; Testori et al. 2002; Herrmann et al. 2005; Sullivan et al. 2005; Malo et al. 2006; Alsaadi et al. 2007) regarded bone quality as synonymous with bone density without present-ing a definition of bone density. The debate about bone quality seems to be more advanced in the literature of osteoporosis (Watts 2002; Recker & Barger-Lux 2004), with a richer notion of bone quality that includes material, mechanical and architectural elements. The combined impact of these factors might equal or exceed that of bone density. In the dental implant field, bone tissue characteristics have also been related to different aspects of bone morphology and biomechanical properties, such as shape (Becker et al. 1997, 1998; Attard & Zarb 2002; Rocci et al. 2003; Bergkvist et al. 2004; Ostman et al. 2006; Herrmann et al. 2007; Alsaadi et al. 2008), degree
of mineralization (Friberg et al. 1995; Choel et al. 2003; Gulsahi et al. 2007) and trabecular or cortical microarchitecture (Razavi et al. 1995; Choel et al. 2004). These studies were performed primarily on human cadaver jaws, which facili-tated not only detailed analyses of different as-pects of jawbone tissue but also the establishment of a reference standard for the assessment method under evaluation.
A number of conclusions can be drawn from our review. First, it has revealed the diversity of classifications of bone tissue characteristics and of methods used to examine and assess jawbone tissue in research concerning dental implants. Second, there is also a lack of consensus with regard to uniform categories and methods among studies when Lekholm & Zarb is referred to. Third, the description of methods used to exam-ine and assess jawbone tissue was frequently scanty and examiner variation when interpreting the findings was not reported. It seems as though there is little understanding of the influence of examiner performance on the outcomes of den-tal implant interventions. The findings of our review suggest a strong need for future uniformity in the design of implant studies. Similar assess-ment methods, classification systems and mea-Table 7. Bone quality
References Classification measurement unit Comments
Assessment method: Only imaging methods mentioned
Lettry et al. (2003) No classification Lettry et al.: Human cadaver jaws. Measurements of mechanical properties and CT scan numbers of fresh mandibles and correlation between them with a view to provide a non-invasive method for determining bone quality for designers of dental implants. CT number and Young’s modulus Degidi et al. (2007) Bone quality as indicated by Misch (1990b)
D1 ¼ thick cortical and dense cancellous bone D2 ¼ thick cortical and fenestrated cancellous bone D3 ¼ thin cortical and dense cancellous bone D4 ¼ thin cortical and fenestrated cancellous bone
Dgidi et al.: Periapical and panoramic radiography, CT
Assessment method: Only examination during drilling/at the time of surgery or fixture insertion mentioned
Khang et al. (2001) Dense Khang et al.: Hand-felt perception of the drilling resistance
Testori et al. (2002) Normal Soft
Testori et al.: Hand-felt perception of the drilling resistance. BQ ¼ bone density. Refer to Trisi & Rao (1999)
Weng et al. (2003) Weng et al.: Hand-felt perception of drilling resistance
Sullivan et al. (2005) Sullivan et al.: Hand-felt perception of drilling resistance.
BQ ¼ bone density
Orsini et al. (2007) Low-density bone (type D3–D4) Orsini et al.: Surgeon’s perception of drilling resistance. BQ ¼ bone density Elkhoury et al. (2005) Bone quality determined on a bone density scale from
1 to 4
Elkhoury et al.: Subjective grading during implant placement Refer to Bra˚nemark et al. (1985) BQ ¼ bone density Assessment method: Not mentioned
Gaucher et al. (2001) Dense (type II) bone Gaucher et al.: No reference to applied classification Normal (type III) bone
Soft (type IV) bone
Manz (1997) Bone quality type: Bone score 1–4 Manz (1997, 2000): No reference to applied classification Manz (2000)
Walker et al. (1997) Bone quality (BQ) 1–4 Walker et al.: No reference to applied classification
Chou et al. (2004) Chou et al.: No reference to applied classification.
BQ ¼ bone density
Ibanez & Jalbout (2002) Bone quality: type I–IV Ibanez & Jalbout: No reference to applied classification Kourtis et al. (2004) Bone quality class D1–D4 Kourtis et al.: No reference to applied classification. Morris et al. (2004) Bone quality classification: Quality-1 – Quality-4 Morris et al.: BQ= bone density
Publications on planning and placement of dental implants where jawbone tissue was described only as bone quality. CT, computed tomography.
surement units are essential prerequisites for comparing the results of different studies and for improving our understanding of treatment out-comes in relation to different bone characteris-tics. If there is no distinct and generally accepted definition of bone tissue characteristics, compar-isons of results cannot be trusted. Moreover, recording of methods to select and generate sam-ples should be reported (Altman et al. 2001; Moher et al. 2001) in order to ensure
representa-tiveness. It should be possible to develop more homogeneous categories in which to place those that are of importance to the treatment outcome. The first step should be the use of more uni-form classification and assessment methods. We propose the classification system presented by Lekholm & Zarb for several reasons: (1) it is well-known; (2) it describes jawbone tissue from both qualitative and quantitative aspects; and (3) re-sults indicate a good correlation with bone
mineral content (Bergkvist et al. 2010). The second step is to validate the classification, ana-lyze diagnostic accuracy and describe observer performance of the method utilized to assess bone tissue. As emphasized in our previous study, a reference method must be identified by which a test method can be validated. To accomplish this, studies on human cadavers are essential.
Whatever classification system is applied and referred to, it should be strictly followed in order Table 8. Bone density
References Classification measurement unit Comments
Assessment method: Computed tomography (CT)
Turkyilmaz et al. (2007a) Bone density measured in HU In the following studies by Turkyilmaz et al. (2006, 2007a, 2007b, 2008a, 2008b) bone density, was measured using software incorporated into CT equipment
Turkyilmaz et al. (2008b) Turkyilmaz et al. (2008a, 2008b): Bone density ¼ bone quality
In following studies: Bone density was correlated with measurements made by insertion torque (N cm) and by resonance frequency (ISQ):
Turkyilmaz et al. (2006) Turkyilmaz et al. (2006): r2¼ 0.27 and 0.22, respectively
Turkyilmaz et al. (2007b) Turkyilmaz et al. (2007b): r ¼ 0.58 and 0.66, respectively
Turkyilmaz et al. (2008a) Turkyilmaz, 2008a r ¼ 0.79–0.87 and 0.82–0-98, respectively
Taguchi et al. (1997) BMD (HU or CT numbers) Taguchi et al.: HU correlated to trabecular bone pattern (grades 1–5) visualized in panoramic radiography
Moheng & Feryn (2005) D1 (low density/quality) D2–D3
D4 (high density/quality)
Moheng & Feryn: Bone density scored using visual inspection and CT-scans: Refer to Misch classification (1990b). Unclear how CT scans was used Assessment method: QCT
Lindh et al. (1996a) HU converted to BMD values (amount of calcium hydroxyapatite in mg/cm3within ROI)
Lindh et al. (1996a): Human cadaver jaws. ROI allocated to trabecular bone tissue
Lindh et al. (1997) Lindh et al. (1997): Human cadaver jaws. BMD correlated with
trabecular bone volume (TBV and TTBV within ROIs expressed as
percentage of mineralized bone tissue) obtained from contact radiography
Homolka et al. (2002) Homolka et al. (2002): Human cadaver jaws. DQCT
(dental quantitative CT). BMD correlated with insertion torque (r2¼ 0.83)
Homolka et al. (2001) Homolka et al. (2001): BMD values converted to color maps
Beer et al. (2003) Beer et al.: Human cadaver jaws. BMD correlated with insertion torque
Kido et al. (1997) HU converted to BMD (mg/cm3) Kido et al.: Human cadaver jaws
Nkenke et al. (2003) HU converted to BMD (mg/cm3) Nkenke et al.: Human cadaver jaws. BMD was correlated with measurements made by insertion torque (N cm), Periotest and by resonance frequency (ISQ). Several parameters were assessed in histomorphometry. Correlations with BMD were not calculated Assessment method: DEXA
Gulsahi et al. (2007) Bone mineral density (BMD, g/cm2) Gulsahi et al.: Jawbone measurements correlated with femoral neck measurements
Bone mineral content (BMC, g/cm)
Assessment method: Weight and volume measurements Misch et al. (1999b) Bone density
Specimen wet weight/specimen structure volume (g/cm3)
Misch et al. (1999b): Human cadaver jaws. Bone density with bone marrow was calculated by dividing
specimen structure volume by the specimen wet weight Assessment method: Radiography and at surgery Misch et al. (1999a) Bone density groups (bone quality)
D1 ¼ most dense bone D2
D3
D4 ¼ least dense bone
Misch et al. (1999a): Panoramic and periapical radiography, lateral cephalography and CT when indicated.
The original classification system according to Misch (1988): D1 ¼ almost all dense compact
D2 ¼ a combination of dense to porous compact cortical bone on the outside and ‘‘coarse’’ trabecular bone on the inside D3 ¼ porous, thinner cortical bone and ‘‘fine’’ trabecular bone D4 ¼ ‘‘fine’’ trabecular bone that has very light density and little or no cortical crestal bone
Assessment method: During surgery/at implant placement
Yang et al. (2008) Dense
Normal Soft
Yang et al.: Surgeon’s hand-felt resistance of bone drilling. Refer to Trisi & Rao (1999); Khang et al. (2001)
Publications on planning and placement of dental implants where jawbone tissue was described only as bone density.
BMD, bone mineral density; BV/TV, trabecular bone volume per tissue volume; CBV/TV, cortical bone volume per tissue volume; CT, computed tomography; HU, Hounsfield units; QCT, quantitative computed tomography; ROI, region of interest; TBPf, trabecular bone pattern factor; TBV, trabecular bone volume; TTBV, total trabecular bone volume.
to enable comparisons and meta-analyses of the results of different studies. Not only bone tissue categories but also the patient sample, the exam-ination methods used and the means of assessing
treatment outcomes should be described, parti-cularly in clinical trials for the purpose of analyz-ing the possible influence of bone tissue characteristics on implant treatment outcomes.
Given that bone characteristics vary within the same jaw (Lindh et al. 2004), we propose that each implant site be assessed and characterized in such clinical trials.
References
Aalam, A.A. & Nowzari, H. (2005) Clinical evaluation of dental implants with surfaces roughened by anodic oxidation, dual acid-etched implants, and machined implants. The International Journal of Oral & Max-illofacial Implants20: 793–798.
Aalam, A.A., Nowzari, H. & Krivitsky, A. (2005) Functional restoration of implants on the day of surgical placement in the fully edentulous mandible: a case series. Clinical Implant Dentistry & Related Research7: 10–16.
Achilli, A., Tura, F. & Euwe, E. (2007) Immediate/early function with tapered implants supporting maxillary and mandibular posterior fixed partial dentures: pre-liminary results of a prospective multicenter study. The Journal of Prosthetic Dentistry97: S52–S58. Alsaadi, G., Quirynen, M., Michiels, K., Jacobs, R. &
van Steenberghe, D. (2007) A biomechanical assess-ment of the relation between the oral implant stability at insertion and subjective bone quality assessment. Journal of Clinical Periodontology34: 359–366. Alsaadi, G., Quirynen, M., Michiles, K., Teughels, W.,
Komarek, A. & van Steenberghe, D. (2008) Impact of local and systemic factors on the incidence of failures up to abutment connection with modified surface oral implants. Journal of Clinical Periodontology 35: 51–57.
Altman, D.G., Schulz, K.F., Moher, D., Egger, M., Davidoff, F., Elbourne, D., G tzsche, P.C. & Lang, T. (2001) The revised CONSORT statement for reporting randomized trials: explanation and elabora-tion. Annals of Internal Medicine 134: 663–694. Aranyarachkul, P., Caruso, J., Gantes, B., Schulz, E.,
Riggs, M., Dus, I., Yamada, J.M. & Crigger, M. (2005) Bone density assessments of dental implant sites: 2. Quantitative cone-beam computerized tomography. The International Journal of Oral & Maxillofacial Implants20: 416–424.
Attard, N.J. & Zarb, G.A. (2002) A study of dental implants in medically treated hypothyroid patients. Clinical Implant Dentistry & Related Research4: 220–231.
Attard, N.J. & Zarb, G.A. (2004) Long-term treatment outcomes in edentulous patients with implant over-dentures: the toronto study. The International Jour-nal of Prosthodontics17: 425–433.
Bahat, O. (2000) Branemark system implants in the posterior maxilla: clinical study of 660 implants followed for 5 to 12 years. The International Journal of Oral & Maxillofacial Implants15: 646–653. Bass, S.L. & Triplett, R.G. (1991) The effects of
pre-operative resorption and jaw anatomy on implant success. A report of 303 cases. Clinical Oral Implants Research2: 193–198.
Becker, B.E., Becker, W., Ricci, A. & Geurs, N. (1998) A prospective clinical trial of endosseous screw-shaped implants placed at the time of tooth extraction without augmentation. Journal of Periodontology 69: 920–926.
Becker, W. & Becker, B.E. (1995) Replacement of maxillary and mandibular molars with single endoss-eous implant restorations: a retrospective study. The Journal of Prosthetic Dentistry74: 51–55. Becker, W., Becker, B.E., Alsuwyed, A. & Al-Mubarak,
S. (1999) Long-term evaluation of 282 implants in maxillary and mandibular molar positions: a prospec-tive study. Journal of Periodontology 70: 896–901. Becker, W., Becker, B.E., Israelson, H., Lucchini, J.P.,
Handelsman, M., Ammons, W., Rosenberg, E., Rose, L., Tucker, L.M. & Lekholm, U. (1997) One-step surgical placement of Branemark implants: a prospec-tive multicenter clinical study. The Internatio-nal JourInternatio-nal of Oral & Maxillofacial Implants12: 454–462.
Becker, W., Becker, B.E., Ricci, A., Bahat, O., Rosen-berg, E., Rose, L.F., Handelsman, M. & Israelson, H. (2000a) A prospective multicenter clinical trial com-paring one- and two-stage titanium screw-shaped fixtures with one-stage plasma-sprayed solid-screw fixtures. Clinical Implant Dentistry & Related Re-search2: 159–165.
Becker, W., Goldstein, M., Becker, B.E. & Sennerby, L. (2005) Minimally invasive flapless implant
surgery: a prospective multicenter study. Clinical Implant Dentistry & Related Research7 (Suppl. 1): S21–S27.
Becker, W., Hujoel, P.P., Becker, B.E. & Willingham, H. (2000b) Osteoporosis and implant failure: an ex-ploratory case-control study. Journal of Perio-dontology71: 625–631.
Beer, A., Gahleitner, A., Holm, A., Tschabitscher, M. & Homolka, P. (2003) Correlation of insertion torques with bone mineral density from dental quantitative CT in the mandible. Clinical Oral Implants Research 14: 616–620.
Bergendal, T. & Engquist, B. (1998) Implant-supported overdentures: a longitudinal prospective study. The International Journal of Oral & Maxillofacial Im-plants13: 253–262.
Bergkvist, G., Koh, K.J., Sahlholm, S., Klintstrom, E. & Lindh, C. (2010) Bone density at implant sites and its relationship to assessment of bone quality and treat-ment outcome. The International Journal of Oral & Maxillofacial Implants25: 321–328.
Bergkvist, G., Sahlholm, S., Nilner, K. & Lindh, C. (2004) Implant-supported fixed prostheses in the edentulous maxilla. A 2-year clinical and radiological follow-up of treatment with non-submerged ITI implants. Clinical Oral Implants Research 15: 351–359.
Bischof, M., Nedir, R., Szmukler-Moncler, S., Bernard, J.P. & Samson, J. (2004) Implant stability measure-ment of delayed and immediately loaded implants during healing. Clinical Oral Implants Research 15: 529–539.
Blanes, R.J., Bernard, J.P., Blanes, Z.M. & Belser, U.C. (2007) A 10-year prospective study of ITI dental implants placed in the posterior region. I: clinical and radiographic results. Clinical Oral Implants Re-search18: 699–706.
Bra˚nemark, P.I., Zarb, G.A., Albrektsson, T. (eds.) (1985) Tissue-integrated prostheses: osseointegration in clinical dentistry. 1st editon, Chicago: Quintes-sence Publishing Co. 356pp.
Bone quality: A classification of the jaws with regard to jawbone quality
recognized four groups - 1 to 4. The assessment methods recommended were the same as suggested for residual jaw shape or contour together with explorative drilling at implant site.
Residual jaw shape or contour: The proposed classification included
five general groups - A to E. Clinical assessment (palpation and probing through the mucosa) and radiography (periapical, panoramic and lateral cephalostatic radiography, and sometimes tomography and occlusal radiography) were recommended
Calandriello, R., Tomatis, M. & Rangert, B. (2003) Immediate functional loading of Branemark system implants with enhanced initial stability: a prospective 1- to 2-year clinical and radiographic study. Clinical Implant Dentistry & Related Research5 (Suppl. 1): 10–20.
Choel, L., Duboeuf, F., Bourgeois, D., Briguet, A. & Lissac, M. (2003) Trabecular alveolar bone in the human mandible: a dual-energy x-ray absorptiometry study. Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology and Endodontics95: 364–370. Choel, L., Last, D., Duboeuf, F., Seurin, M.J., Lissac,
M., Briguet, A. & Guillot, G. (2004) Trabecular alveolar bone microarchitecture in the human mandible using high resolution magnetic reso-nance imaging. Dentomaxillofacial Radiology 33: 177–182.
Chou, C.T., Morris, H.F., Ochi, S., Walker, L. & DesRosiers, D. (2004) AICRG, part II: Crestal bone loss associated with the ankylos implant: loading to 36 months. The Journal of Oral Implantology 30: 134–143.
Collaert, B. & De Bruyn, H. (2008) Immediate func-tional loading of TiOblast dental implants in full-arch edentulous maxillae: a 3-year prospective study. Clin-ical Oral Implants Research19: 1254–1260. Degidi, M., Piattelli, A., Iezzi, G. & Carinci, F. (2007)
Do longer implants improve clinical outcome in immediate loading? The International Journal of Oral and Maxillofacial Surgery36: 1172–1176. Dorland’s Illustrated Medical Dictionary, 31st edition,
Philadelphia, W. B. Saunders, p. 2088, 2007 Elkhoury, J.S., McGlumphy, E.A., Tatakis, D.N. &
Beck, F.M. (2005) Clinical parameters associated with success and failure of single-tooth titanium plasma-sprayed cylindric implants under stricter cri-teria: a 5-year retrospective study. The International Journal of Oral & Maxillofacial Implants20: 687– 694.
Engquist, B., Bergendal, T., Kallus, T. & Linden, U. (1988) A retrospective multicenter evaluation of osseointegrated implants supporting overdentures. The International Journal of Oral & Maxillofacial Implants3: 129–134.
Fartash, B., Tangerud, T., Silness, J. & Arvidson, K. (1996) Rehabilitation of mandibular edentulism by single crystal sapphire implants and overdentures: 3– 12 year results in 86 patients. A dual center interna-tional study. Clinical Oral Implants Research 7: 220–229.
Friberg, B. (1994) Bone quality evaluation during im-plant placement.Thesis, University of Gothenburg, Gothenburg, 41pp.
Friberg, B. Billstro¨m, C. (2002) Preliminary results of a prosperative multicenter clinical study on TiUnite implants. Applied Osseointegration Research 3: 29–31.
Friberg, B., Dahlin, C., Widmark, G., Ostman, P.O. & Billstrom, C. (2005) One-year results of a prospective multicenter study on Branemark System implants with a TiUnite surface. Clinical Implant Dentistry & Related Research7 (Suppl. 1): S70–S75. Friberg, B., Ekestubbe, A. & Sennerby, L. (2002)
Clin-ical outcome of Branemark System implants of var-ious diameters: a retrospective study. The International Journal of Oral & Maxillofacial Im-plants17: 671–677.
Friberg, B., Grondahl, K. & Lekholm, U. (1992) A new self-tapping Branemark implant: clinical and
radio-graphic evaluation. The International Journal of Oral & Maxillofacial Implants7: 80–85.
Friberg, B., Jemt, T. & Lekholm, U. (1991) Early fail-ures in 4,641 consecutively placed Branemark dental implants: a study from stage 1 surgery to the connec-tion of completed prostheses. The Internaconnec-tional Jour-nal of Oral & Maxillofacial Implants6: 142–146. Friberg, B., Jisander, S., Widmark, G., Lundgren, A.,
Ivanoff, C.J., Sennerby, L. & Thoren, C. (2003) One-year prospective three-center study comparing the outcome of a ‘‘Soft bone implant’’ (prototype Mk IV) and the standard Branemark implant. Clinical Implant Dentistry & Related Research5: 71–77.
Friberg, B., Sennerby, L., Grondahl, K., Bergstrom, C., Back, T. & Lekholm, U. (1999) On cutting torque measurements during implant placement: a 3-year clinical prospective study. Clinical Implant Dentistry & Related Research1: 75–83.
Friberg, B., Sennerby, L., Roos, J. & Lekholm, U. (1995) Identification of bone quality in conjunction with insertion of titanium implants. A pilot study in jaw autopsy specimens. Clinical Oral Implants Research 6: 213–219.
Ganeles, J., Zollner, A., Jackowski, J., ten Bruggenkate, C., Beagle, J. & Guerra, F. (2008) Immediate and early loading of Straumann implants with a chemically modified surface (SLActive) in the posterior mandible and maxilla: 1-year results from a prospective multi-center study. Clinical Oral Implants Research 19: 1119–1128.
Gaucher, H., Bentley, K., Roy, S., Head, T., Blomfield, J., Blondeau, F., Nicholson, L., Chehade, A., Tardif, N. & Emery, R. (2001) A multi-centre study of Osseotite implants supporting mandibular restora-tions: a 3-year report. Journal of the Canadian Dental Association67: 528–533.
Goodman, C. (1996) Literature searching and evidence interpretation for assessing health care practices. The Swedish Council on Technology Assessment in Health Care, Stockholm.
Grunder, U., Polizzi, G., Goene, R., Hatano, N., Henry, P., Jackson, W.J., Kawamura, K., Kohler, S., Re-nouard, F., Rosenberg, R., Triplett, G., Werbitt, M. & Lithner, B. (1999) A 3-year prospective multicenter follow-up report on the immediate and delayed-im-mediate placement of implants. The International Journal of Oral & Maxillofacial Implants14: 210– 216.
Gulsahi, A., Paksoy, C.S., Yazicioglu, N., Arpak, N., Kucuk, N.O. & Terzioglu, H. (2007) Assessment of bone density differences between conventional and bone-condensing techniques using dual energy x-ray absorptiometry and radiography. Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology and En-dodontics104: 692–698.
Herrmann, I., Kultje, C., Holm, S. & Lekholm, U. (2007) A study on variances in multivariate analyses of oral implant outcome. Clinical Implant Dentistry & Related Research9: 6–14.
Herrmann, I., Lekholm, U., Holm, S. & Kultje, C. (2005) Evaluation of patient and implant characteris-tics as potential prognostic factors for oral implant failures. The International Journal of Oral & Max-illofacial Implants20: 220–230.
Homolka, P., Beer, A., Birkfellner, W., Gahleitner, A., Nowotny, R. & Bergmann, H. (2001) Local calibrated bone mineral density in the mandible presented using
a color coding scheme. Medical Engineering & Physics23: 673–677.
Homolka, P., Beer, A., Birkfellner, W., Nowotny, R., Gahleitner, A., Tschabitscher, M. & Bergmann, H. (2002) Bone mineral density measurement with den-tal quantitative CT prior to denden-tal implant placement in cadaver mandibles: pilot study. Radiology 224: 247–252.
Horner, K. & Devlin, H. (1998) The relationships between two indices of mandibular bone quality and bone mineral density measured by dual energy x-ray absorptiometry. Dentomaxillofacial Radiology 27: 17–21.
Hutton, J.E., Heath, M.R., Chai, J.Y., Harnett, J., Jemt, T., Johns, R.B., McKenna, S., McNamara, D.C., van Steenberghe, D. Taylor, R., Watson, R.M., Herrmann, I. (1995) Factors related to success and failure rates at 3-year follow-up in a multicenter study of overden-tures supported by Branemark implants. The Interna-tional Journal of Oral & Maxillofacial Implants10: 33–42.
Huwiler, M.A., Pjetursson, B.E., Bosshardt, D.D., Salvi, G.E. & Lang, N.P. (2007) Resonance frequency ana-lysis in relation to jawbone characteristics and during early healing of implant installation. Clinical Oral Implants Research18: 275–280.
Ibanez, J.C. & Jalbout, Z.N. (2002) Immediate loading of Osseotite implants: two-year results. Implant Dentistry11: 128–136.
Ivanoff, C.J., Grondahl, K., Sennerby, L., Bergstrom, C. & Lekholm, U. (1999) Influence of variations in implant diameters: a 3- to 5-year retrospective clinical report. The International Journal of Oral & Maxillo-facial Implants14: 173–180.
Jaffin, R.A. & Berman, C.L. (1991) The excessive loss of Branemark fixtures in type IV bone: a 5-year analysis. Journal of Periodontology62: 2–4.
Jagger, R.G., Shaikh, S. & Jagger, D.C. (2001) Clinical effectiveness of mandibular implant-retained overden-tures. Prima Dental Care 8: 19–24.
Jemt, T. (1993) Implant treatment in resorbed edentu-lous upper jaws. A three-year follow-up on 70 patients. Clinical Oral Implants Research 4: 187– 194.
Jemt, T. (1994) Fixed implant-supported prostheses in the edentulous maxilla. A five-year follow-up report. Clinical Oral Implants Research5: 142–147. Jemt, T. & Hager, P. (2006) Early complete failures of
fixed implant-supported prostheses in the edentulous maxilla: a 3-year analysis of 17 consecutive cluster failure patients. Clinical Implant Dentistry & Re-lated Research8: 77–86.
Jemt, T. & Lekholm, U. (1995) Implant treatment in edentulous maxillae: a 5-year follow-up report on patients with different degrees of jaw resorption. The International Journal of Oral & Maxillofacial Im-plants10: 303–311.
Johansson, P. & Strid, K.G. (1994) Assessment of bone quality from cutting resistance during implant sur-gery. The International Journal of Oral & Maxillo-facial Implants9: 279–288.
Johns, R.B., Jemt, T., Heath, M.R., Hutton, J.E., McKenna, S., McNamara, D.C., van Steenberghe, D., Taylor, R., Watson, R.M. & Herrmann, I. (1992) A multicenter study of overdentures supported by Branemark implants. The International Journal of Oral & Maxillofacial Implants7: 513–522. Khang, W., Feldman, S., Hawley, C.E. & Gunsolley, J.
